We have developed methods to separate certain antigens present in culture filtrates of tubercle bacilli. Multiple mycobacterial antigens, at least 5, are already recognized, each apparently able to elicit tuberculin reactions in sensitized guinea pigs owing to parallel, independent sensitivities. We are able to pilot the purification procedure by a unique method employing passive cutaneous anaphylaxis in guinea pigs prepared with a selected "pane of antisera of different specificities, using as test antigen the fraction to be evaluated. These antigens will be evaluated by (a) comparison with the reference system proposed by Janicki et al (1971), (b) studies as elicitors of delayed hypersensitivity in guinea pigs "minimally" and "maximally" sensitized with different mycobacterial strains, against 0.5 micron g Merck PPD as standard, and (c) ascertaining the capacity for inhibiting macrophage migration in lymphocyte-macrophage mixtures from tuberculin-sensitive animals. Study of claims of "transfer" of hypersensitivity with non-dialyzable fractions of serum will be extended to examining sera from the few guinea pigs which become highly sensitive to tuberculin yet do not develop discernible anti-mycobacterial antibodies. It is nearly impossible to analyze for traces of delayed hypersensitivity in 24-hour readings on plasma recipients among residua of early reactions which have already occurred upon PPD-testing. We propose 1:1 transfers, i.e., one donor's plasma to 1 recipient, and evaluation of each donorfor presence of the 5 presently recognized antimycobacterial antibodies. Skin tests will include isolated "Antigen-3" which we regard as the true "PPD", since PPD preparations contain other antigens as well. Dupuy et al (1969,1970b) claim that soaking lymphoid cells in plasma and transferring the washed cells will effect, irregularly, transfer of delayed hypersensitivity. We shall try to separate such agent from the usual welter of antibodies present in most starting sera. The procedure of Burger and Jetter (1971) for securing dialyzable guinea pig "transfer factor" will be evaluated.